The present invention relates to a twin boom for a sailing surfboard with a trapezoidal member fixed at at least one of its two twin boom tubes with its two ends adjacent to the rear twin boom tube connection and to the twin boom grip with a slack portion for hooking in a hook fixed to the vest, suit or retaining belt worn by the wind surfer.
It is known to fix a trapezoidal member to a twin boom tube of a twin boom of a sailing surfboard. The trapezium in conjunction with the trapezoidal member makes it possible to free the hands and arms of the surfer, if he is hooked onto the trapezoidal member by a hook fixed to a vest, suit or retaining belt worn by him, so that the sail can be held by the surfer's body. This permits surfing at high wind speed and for long periods without any fatigue to the surfer.
It is known to knot the trapezoidal member directly to the twin boom tube of the twin boom. By means of tapes which are wound several times round the twin boom tube and end in loops, or tapes which are joined in sleeve-like manner to the twin boom by adhesive fastening and have loops or by U-shaped plastic stirrups having in their end areas bores for fixing the trapezoidal member, the latter is held on the twin boom tube for forming a slack portion.
It is a disadvantage of all these constructions that the rubber covering surrounding the twin boom tube is displaced under stress and is detached. In addition, the trapezoidal member cannot be rapidly and adequately trimmed during surfing. For this purpose, the fixing points for the trapezoidal member must be released by opening the knots in order to be able to displace the fixing points and in addition the two fixing points for the trapezoidal member must be displaced in order to restore the slack portion thereof. It is necessary to trim the trapezoidal member after a sail change, on changing course, in the case of a wind change and for special surfing techniques, such as e.g. jumping.
Importance is attached in this connection to the slack portion of the trapezoidal member, the spacing of the engagement or working points of the trapezoidal member and the position of said points on the twin boom tube.
A further disadvantage is that the fixing points of the trapezoidal member to the twin boom and which are located in the gripping area of the hands have a prejudicial action. In addition, the trapezoidal member is essentially loaded in a small area by the vest hook and after a short time chafes through the trapezoidal member at this point.